The first time you cast any spell that lets you see unseen things, it also gives you Wizard Vision. This is a one-way road, and it is permanent. Things that have been seen cannot be unseen.

The first time a wizard casts any sort of -sight or detect spell on himself, he gains Wizard Vision (except for detect magic, that one's safe). Then, you have a choice to make. You can accept the weird meta-reality that lurks behind our own, or you can reject it.

Reject: Lose 1d6 Wisdom as cognitive dissonance makes you loopy.

Accept: Lose 1d6 Charisma as impossible sights assail your humanity.

In exchange, you gain two new powers:

Can cast detect invisibility at will, and with a thought.

Know if another creature is a spellcaster or not by looking them in the eye.

Let's not talk about how balanced this is, and instead talk about how cool it is.